Measuring Vitamin D in the Brain Using Chromatography

Vitamin D is an essential component for a healthy life. We all need it. In the UK, many of us can get enough vitamin D during the summer months from our exposure to sunlight. Outside the sunny summer months, we can get a little help from the foods we eat or by taking a supplement. The UK government recommends taking a supplement for several groups that are considered vulnerable to vitamin D deficiencies.

But traditional vitamin D tests tell you the concentration of vitamin D in serum, what about the level of vitamin D in the organs that it might affect? A recent paper published in the journal Current Developments in Nutrition - Determination of vitamin D and its metabolites in human brain using an ultra-pressure liquid chromatography-tandem mass spectra method - used chromatography to try and answer this question.

The sunshine nutrient

Vitamin D is essential to help us to live healthy lives. It is one of the most important nutrients helping to regulate how much calcium and phosphate we make use of in the body. It is a lack of vitamin D that leads to bone deformities include the condition known as rickets in children - and in adults it can cause bone pain due to a condition known as osteomalacia,

But, vitamin D deficiency is also associated with other diseases and conditions. It has previously been suggested that low levels of vitamin D metabolites in serum could be associated with Alzheimer’s Disease and also with cognitive impairment. In animal models using rats, a link between serum and brain levels of 25(OH)D₃ has been confirmed - but not in humans yet. The study referenced above set out to try and validate a method to quantify vitamin D and its metabolites in the human brain. And chromatography was key.

Dissecting the brain for sunshine vitamins

The method the team developed and validated was used to analyse vitamin D and its metabolites in a human brain donated by a French donor. The brain was dissected into its different regions and analysed for vitaminD₃ and the metabolites 25-hydroxy vitamin D3 and 1,25 dihydroxy vitamin D3. The brain samples were first homogenized before any vitamin D and its metabolites were extracted using various solvents.

The samples were then analysed using liquid chromatography-tandem mass spectrometry (LC-MS/MS). Improving liquid chromatography analysis is the topic in the article, Using Narrow Bore Columns to Enhance Sensitivity for LC-UV and LC-MS Analyses.  The team conclude:

To the best of our knowledge, this study is the first report of the measurement of concentrations of vitamin D metabolites in human brain. This validated method can be applied to post-mortem studies to obtain accurate information about the presence and role of vitamin D and metabolites in human brain and neurodegenerative diseases